"Developmental delay" means a disability affecting a child ages two by September 30 through six inclusive:
(i) Who is experiencing developmental delays, as measured by appropriate diagnostic instruments and procedures, in one or more of the following areas: physical development, cognitive development, communication development, social or emotional development, or adaptive development, or (ii) who has an established physical or mental condition that has a high probability of resulting in developmental delay;
The delay(s) is not primarily a result of cultural factors, environmental or economic disadvantage, or limited English proficiency; and
The presence of one or more documented characteristics of the delay has an adverse effect on educational performance and makes it necessary for the student to have specially designed instruction to access and make progress in the general educational activities for this age group.
Delay in one or more of the following areas: cognitive development, physical development, social/emotional development, or adaptive development
Significant delays or atypical patterns of development
Physical or mental condition that has a high probability of resulting in developmental delay
Fast Facts: Developmental Delay: Why the age of eligibility changed from ages 2 through 8, inclusive to 2 through 6 (PDF) – State guidance to assist eligibility teams in accurately identifying students.